OBJECTIVES: To continue the investigation of the fundamental properties and the involvement of airway smooth muscle in diseased lungs; and to understand the role of airway smooth muscle in normal lungs and lungs with airway obstruction. SPECIAL INTERESTS: (1) Defining the indices affecting the reactivity and/or contractility of normal airway smooth muscle. In particular this project will investigate: (a) the metabolic properties of airway smooth muscle; (b) the role of calcium, pH, PCO2 and PO2; and (c) the electrical properties of airway smooth muscle cells. (2) Defining the indices affecting the reactivity and/or contractility of airway smooth muscle under pathological conditions. The effect of experimental asthma ("chronic" experimental asthma) on the reactivity and/or contractility of airway smooth muscle will be studied. The role of smooth muscle hypertrophy and hyperplasia in the reactivity and/or contractility of airway smooth muscle will be determined. The involvement of airway smooth muscle in the airway hyper-reactivity of asthmatic lungs will also be determined. (3) Investigating the role of airway diameter in the reactivity and/or contractility of airways in normal and asthmatic lungs. Employing bronchi of different calibers, the physiological, pharmacological and biochemical responses to different stimuli and pharmacological blockers will be studied. (4) Defining the species differences in airway smooth muscle reactivity and/or contractility. Bronchi from several species will be used. (5) Studying the role of spontaneous mechanical activities of airway smooth muscle isolated from normal and abnormal lungs.